Go on Rte 233 (Eagle Lake Road), past Parsons Lobster on the left, past Kebo Mountain Golf Course on the left, past the Park Entrance on the right, and staying on 233, after about three miles (my rough guess), you'll come to a parking area for Eagle Lake on your right.
After you exit your car and follow the obvious path, you'll come to a left or right hand choice. Go left. When you come to a fork, stay to your left.
Turn around when you think it's time! Don't keep going... the entire trip around the lake is probably ten miles!